JP2004015257A - Content reproducing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a content reproducing apparatus capable of starting reproduction of contents in a short time. <P>SOLUTION: The content reproducing apparatus 10 includes a CPU 18, and the CPU 18 executes authentication processing with a memory card 12 at start of reproduction processing. When achieving success in the authentication processing, the reproducing apparatus 10 can acquire a decoding key of encrypted music data from the memory card 12. Thus, the reproducing apparatus 10 can use the decoding key of encrypted contents data separately acquired to decode the data and reproduce music data. In the authentication processing above, certificate data are used in the order started from certificate data corresponding to a registered identification number and the identification number is revised into a succeeding identification number every time the authentication processing is failed. As a result, the identification number of the certificate data achieving success in the authentication processing is registered and used for the next and succeeding authentication processing. Since the reproducing apparatus does not use the certificate data that cannot be used, the wasteful authentication processing can be omitted and the reproducing apparatus can start reproduction in a short time. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention relates to a content reproducing apparatus, and more particularly to a content reproducing apparatus that executes authentication processing using, for example, certificate data with a removable recording medium and reproduces the content of the recording medium when the authentication processing is successful.
[0002]
[Prior art]
An example of this type of conventional content reproducing apparatus is disclosed in Japanese Patent Application Laid-Open No. 2002-26900 [H04L 9/32, G06F 12/14, G10L 19/00, H04N 5 /], which was published on Jan. 25, 2002. 91, H04N 5/92]. As shown in FIG. 8, the data reproducing apparatus 1 is provided, for example, in a mobile phone 2. The data reproducing device 1 executes a reproducing process of encrypted music data (encrypted music data) stored in the memory card 3 according to an instruction from a user. The controller 4 reads the authentication data {KPpx // Crtfx} KPma from the authentication data holding unit 6 and inputs this to the memory card 3 via the memory interface 7. For example, the authentication data holding unit 6 holds two pieces of authentication data of {KPp1 // Crtf1} KPma and {KPp2 // Crtf2} KPma, and the controller 4 sends the {KPp1 // Crtf1} KPma, {KPp2 // The authentication data is read in the order of Crtf2 @ KPma.
[0003]
On the other hand, the memory card 3 receives the authentication data {KPpx // Crtfx} KPma input from the mobile phone 2 and performs a decryption process. That is, the received authentication data {KPpx // Crtfx} KPma is decrypted by the public authentication key KPma. Using this decryption result, it is determined whether or not the authentication data {KPpx // Crtfx} KPma is legitimate authentication data. If the authentication data cannot be decrypted in the memory card 3, an output of rejection of the authentication data is given from the memory card 3 to the controller 4. On the other hand, when the authentication data has been successfully decrypted, the memory card 3 determines whether or not the obtained certificate Crtfx is included in the prohibited class list data.
[0004]
The certificate Crtfx is provided with an ID, and the memory card 3 determines whether or not the ID of the received certificate Crtfx exists in the prohibited class list data. When the certificate Crtfx is included in the prohibition class list data, the memory card 3 provides an output of rejection of the authentication data to the mobile phone 2, that is, the controller 4.
[0005]
As described above, when the authentication data cannot be decrypted with the public authentication key KPma, or when the accepted certificate Crtfx is included in the prohibition class list data, the memory card 3 determines that the authentication data has not been accepted by the mobile phone 2. Output to Therefore, when receiving the authentication data rejection, the controller 4 reads the next authentication data. As described above, since the controller 4 first reads the authentication data {KPp1 // Crtf1} KPma, the next (other) authentication data {KPp2 // Crtf2} KPma is read instead. Until it is determined that the certificate Crtfx is not included in the prohibition class list data, or until all the authentication data is output, the next authentication data is read, that is, the certificate Crtf1, the certificate Crtf2,. The illumination data including the certificate Crtfx is sequentially read, and the above-described authentication processing is repeated.
[0006]
Here, the fact that the certificate Crtfx is included in the prohibited class list data means that the secret decryption key Kpx as the class key has been broken by decryption or leakage. Since the memory card 3 cannot output the encrypted music data to the data reproducing device 1 holding such a broken certificate, the certificate received from the mobile phone 2 is not included in the prohibited class list data. Until it is confirmed that it has not been done, it does not move to the next step.
[0007]
That is, after the authentication data rejection is output from the memory card 3, the controller 4 sets another (next) authentication data to be transmitted to the memory card 3. Even if one or more of them are included in the prohibited class list data, if another certificate is not included in the prohibited class list data, the encrypted content data and the license key are received from the memory card 3. Music data. In this manner, even if the certificate is included in the prohibited class list data by decrypting or leaking the secret decryption key, the life of the mobile phone 2 including the data reproducing device 1 is extended.
[0008]
[Problems to be solved by the invention]
However, in this prior art, when performing authentication processing with the memory card 3, the data reproducing apparatus 1 uses the certificate in a predetermined order, so that the prohibition class held by the memory card 3 is used. Even a certificate that is already included in the list data and cannot be used may be transmitted to the memory card 3 side. In this case, the memory card 3 fails in the authentication and outputs a rejection of the proof data. For this reason, the time during that time, particularly the time required for the decryption processing of the certificate, is wasted, causing a problem that the reproduction start of the music data (content data) is unnecessarily delayed.
[0009]
Therefore, a main object of the present invention is to provide a content reproducing apparatus that can start reproducing content in a short time.
[0010]
[Means for Solving the Problems]
According to the present invention, in a content reproducing apparatus that performs authentication processing using certificate data with a detachable recording medium and reproduces the content of the recording medium when the authentication processing is successful, the content reproduction apparatus performs the processing corresponding to the registered identification number. Means for executing authentication processing in the order starting from the certificate data to be authenticated, specifying means for specifying the identification number of unused certificate data when the authentication processing fails, and identifying the registered identification number by the specifying means A content reproducing apparatus comprising an updating unit for updating to a number.
[0011]
[Action]
At the start of the playback process, the content playback device executes an authentication process using certificate data with a removable recording medium such as a memory card. When such authentication processing is successful, the content (music, image, etc.) from the recording medium can be reproduced. In the authentication process, the certificate data is used in the order starting from the certificate data corresponding to the registered identification number. If the authentication process fails, the identification number of the unused certificate data is specified. When the identification number is specified, the registered identification number is updated to the identification number specified by the specifying means. That is, the identification numbers of the certificate data not used in the authentication processing are registered and used in the next and subsequent authentication processing. In other words, there is no need to perform authentication processing using a certificate that can no longer be used.
[0012]
For example, when the authentication processing has failed, the specifying means specifies the identification number corresponding to the next certificate data, and the identification number is updated at this time. An identification number can be registered. Therefore, in the subsequent authentication processing, the authentication processing hardly fails unless registered in the prohibition list.
[0013]
Further, the content is encrypted for protection by copyright. Therefore, when the authentication process is successful, a decryption key for decrypting the encrypted content is obtained. Therefore, the decryption means can decrypt the encrypted content using the decryption key.
[0014]
【The invention's effect】
According to the present invention, certificate data that has already become unusable is not used for authentication processing. Even if certificate data corresponding to the stored identification number becomes unusable, it is no longer usable. Since the authentication processing is not performed using the certificate data that has been used, unnecessary authentication processing can be avoided. That is, the authentication process can be completed in a minimum necessary time, so that the reproduction can be started in a short time.
[0015]
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.
[0016]
【Example】
With reference to FIG. 1, a content reproducing apparatus (hereinafter, simply referred to as a “reproducing apparatus”) 10 of this embodiment includes a memory card 12, and the memory card 12 is detachably provided to the reproducing apparatus 10. The memory card 12 is inserted into a slot 14 provided in the playback device 10 and connected to a CPU 18 via a memory interface (I / F) 16.
[0017]
An operation key 20 is connected to the CPU 18, and by operating the operation key 20, the mode is switched, and instructions such as recording (recording), reproduction, stop, forward (FF), and return (RW) are issued. Can be entered.
[0018]
Further, an analog input terminal (jack terminal) 24 is connected to the CPU 18 via an A / D converter 22. A music player such as a CD player, an MD player, or a component (mini component) (not shown) can be connected to the analog terminal 24. The analog music signal reproduced from the music reproducing device connected in this way is converted into digital music data by the A / D converter 22, and the music data is subjected to predetermined processing, and then is processed via the CPU 18. The data is transferred to the memory card 12 and recorded.
[0019]
However, since such music data is protected by copyright and it is necessary to pay a copyright fee to the copyright holder, predetermined processing such as encryption will be described later in detail. And other measures are taken.
[0020]
Since the technique for recording music data on the memory card 12 is well known, a detailed description thereof will be omitted in this embodiment. Although not shown, the playback device 10 is provided with a USB terminal. By connecting a PC to the USB terminal, music data downloaded by the PC can be recorded on the memory card 12.
[0021]
A liquid crystal display 28 is connected to the CPU 18 via a driver 26. The display 28 includes a current time (calendar), an operation state during reproduction (reproduction, stop, FF or RW, etc.), information indicating recording, a battery remaining amount, a volume, a reproduction list, a name of a song being reproduced, and related information. Information (related information; singer name, lyrics, lyrics / composer name, jacket image) and the like are displayed.
[0022]
Here, the reproduction list refers to a menu (list) of music titles and the like of music data stored in the memory card 12. Using this playlist, the user selects a song to be played.
[0023]
As will be described later in detail, the memory card 12 stores at least encrypted content data (music data in this embodiment) and a content decryption key for decrypting the encrypted content data. The memory card 12 also stores unencrypted music data. Such music data follows an arbitrary compression format, such as MP3 or AAC, and is compressed at an arbitrary compression rate (bit rate). That is, the encrypted music data (encrypted music data) is compressed and then subjected to an encryption process.
[0024]
For example, the playback device 10 is configured as shown in FIG. 2, and the user operates a mode (mode) key 20 b included in the operation keys 20 to set the sound quality of the music to be recorded / reproduced, You can set the display method. At this time, the user can determine what setting has been made by looking at the display on the display 28. In setting, a desired setting can be selected by operating the jog dial 20a and the volume keys 20b and 20c.
[0025]
When the user operates a recording (REC) key 20e included in the operation keys 20, the playback device 10 starts recording. That is, a music signal (input signal) reproduced from the music reproducing device connected to the input terminal 24 is input via the input terminal 24, converted into digital data by the A / D converter 22, and provided to the CPU 18. Then, after being encoded (compressed) and encrypted according to instructions and processing of the CPU 18, the data is transferred to the memory card 12 and recorded.
[0026]
However, the compression process is executed by the DSP 30 under the instruction of the CPU 18, and the music data is compressed according to an arbitrary compression method such as MP3 or AAC and at an arbitrary compression rate (bit rate). The music data that has undergone such compression processing is further encrypted by the CPU 18 and then recorded on the memory card 12 via the memory I / F 16.
[0027]
When the recording of the encrypted music data (encrypted music data) ends, the CPU 18 generates a decryption key (content decryption key) for decrypting each of the recorded encrypted music data, and outputs the content decryption key. And license data including reproduction conditions of encrypted music data and the like are recorded on the memory card 12.
[0028]
By operating the PC connected to the USB terminal, the encrypted music data downloaded to the PC and the license data as described above can be recorded on the memory card 12 via the CPU 18.
[0029]
When a stop (STOP) key 20f included in the operation keys 20 is operated during recording, the recording enabled state is released. That is, recording becomes impossible.
[0030]
On the other hand, in the case of reproduction, although not shown, a cursor for selecting a reproduction list and music (music) as described above can be displayed on the display 28. Here, when the user rotates the jog dial 20a included in the operation keys 20 to either one, the cursor is scrolled up and down on the screen of the display 28, so that a desired song can be selected. Next, when the jog dial 20a is pressed (turned on), that is, when a reproduction instruction is input, the reproduction processing of the music pointed to by the cursor is started.
[0031]
In this way, the CPU 18 starts the reproduction process. When reproducing the encrypted music data, the CPU 18 executes an authentication process described later in detail with the memory card 12 before starting the reproduction. . In short, since the memory card 12 is detachable from the playback device 10, it is determined whether the playback device 10 is a proper one, that is, whether the playback device 10 has a correct certificate (information). The memory card 12 itself has confirmed (authenticated).
[0032]
For example, when playing back encrypted music data, an authentication process is first performed between the playback device 10 and the memory card 12, and if authentication is successful, the memory card 12 sends the encrypted data to the CPU 18 via the I / F 16. Music data and its content decryption key are provided. Upon receiving the encrypted music data and the content decryption key, the CPU 18 decrypts the encrypted music data with the content key (plaintext), and provides the decrypted music data to the DSP 30. Further, the CPU 18 reads out decoding software (decoding) stored in the EEPROM 40 and according to the music data compression format, and provides the software to the DSP 30. Therefore, the DSP 30 decodes the music data using the decoding software. The decoded music data is converted by a D / A converter 32 into an analog music signal. The converted music signal is amplified by an audio amplifier (AMP) 34 and then input from an output terminal (jack terminal) 36 to a headphone 38. This allows the user to listen to the song whose reproduction has been instructed.
[0033]
In the case of reproducing music data that has not been encrypted, if the above-described authentication processing is successful, the CPU 18 reads the music data from the memory card 12 via the I / F 16. The CPU 18 acquires the decoding software for the music data from the EEPROM 40 and supplies the software together with the music data to the DSP 30. Subsequent processing is the same as the above-described processing for the encrypted music data, and thus redundant description will be omitted.
[0034]
During playback of music data, when the jog dial, that is, the key 20a is rotated in one direction, fast forward playback is performed or the next song is sent. On the other hand, when the key 20a is rotated in the opposite direction, rewind playback or return to the previous song is performed. When the jog dial 20a is pressed during the reproduction of the music data, the reproduction is paused, and when the jog dial 20a is pressed again, the reproduction is resumed. Further, by operating the volume (Vol-, Vol +) keys 20c and 20d included in the operation keys 20, the volume of the music being reproduced can be reduced or increased. By operating the stop key 20f, the reproduction of the music can be stopped (terminated).
[0035]
The memory card 12 is, for example, a secure multimedia card, and includes a controller 50 as shown in FIG. The controller 50 is connected to a memory 54, a license memory 56, and a key memory 58 via an internal bus 52. The memory 54 stores data that can be freely exchanged, such as the above-described encrypted music data and music data that has not been encrypted. The license memory 56 stores data necessary for protecting the copyright such as a content decryption key, that is, license data required for reproducing the encrypted music data, and a certificate for which the use has been prohibited (revoked). And data (revocation list data) listing IDs (certificate IDs). Further, the key memory 58 stores a public authentication key for use in mutual authentication (encryption) processing for exchanging license data. The license memory 56 and the key memory 58 are formed in an area (secure area) that cannot be accessed by a user operation.
[0036]
Here, as the music data not subjected to encryption, for example, music data corresponding to a short song such as a pickup of a part of a song scheduled to be distributed or being distributed for an advertisement or free of charge to an individual. In the case of providing a self-made song, music data or the like corresponding to the song is applicable.
[0037]
As described above, the encrypted music data and the unencrypted music data are mixed, and whether or not the encrypted music data is encrypted is determined by whether the encrypted music data or the header of the music data is encrypted. Since the information (tag) for identifying the information is attached, it can be easily known (determined).
[0038]
In this embodiment, the license data means a content decryption key (Kc (n)), control information (AC1), control information (AC2), a license ID, and a content ID. The content decryption key (Kc (n)) (n is a natural number of 1 or more) is a key (key) for decrypting the encrypted music data, and is individually prepared for the n pieces of encrypted music data. .
[0039]
Further, the restriction information (AC1) includes permission information for determining whether the content decryption key (Kc (n)) stored in the memory card 12 may be output, and a frequency limit for restricting the number of times of reproduction. Contains information.
[0040]
The frequency limit information is set, for example, in one-byte data, that is, between “00” and “FF”. When the number-of-times restriction information is “00”, it indicates that reproduction is not possible, and when “FF”, it indicates that there is no restriction on the number of reproductions. Further, the number of times of reproduction is limited between “01” and “FE”. More precisely, the number of times the content decryption key (Kc (n)) is output is limited.
[0041]
The control information (AC2) is information indicating a reproduction limit on the reproduction circuit side such as a reproduction time limit (term). Specifically, the playback time limit limits the date and time at which playback is possible.
[0042]
Further, the license ID is a management code capable of specifying issuance of a license, and the content ID is an identification code for identifying content data, that is, (encrypted) music data.
[0043]
Such license data and the above-mentioned revocation list data are acquired when the PC downloads the encrypted music data. At this time, information on the music data, that is, related information is also downloaded together with the encrypted music data.
[0044]
For revocation list data, all revocation lists may be downloaded each time.However, since the amount of data is enormous, only the difference between the previously downloaded revocation list and the latest revocation list should be downloaded. May be.
[0045]
When music data is acquired from a music CD mounted on the music playback device, the playback device 10 encrypts the music data, generates license data and revocation list data, and stores these data in the memory. It is input to the card 12 side.
[0046]
The reproduction device 10 will be described in detail. As shown in FIG. 1, the CPU 18 is connected to the memory card 12 via the I / F 16 to obtain the content decryption key (Kc (n)) and the control information (AC2). A key is exchanged with the memory card 12 to perform mutual authentication. Further, a key memory 42 and a DSP 30 as a content decryption processing circuit are connected to the CPU 18. The key memory 42 stores certificate data (KPp (n, a)) and a secret decryption key (kp (n)). The CPU 18 acquires the encrypted music data ({Data} Kc (n)) from the memory card 12 in addition to the content decryption key (Kc (n)), and encrypts the data using the content decryption key (Kc (n)). The music data (¥ Data ¥ Kc (n)) is decrypted (plain culture). Then, the music data (Data) decoded by the predetermined decoding software in the DSP 30 is converted into an analog music signal by the D / A converter 32, amplified by the AMP 34, and output to the output terminal 36.
[0047]
Note that the certificate data (KPp (n, a)) is synonymous with the public encryption key unique to the class (type, manufacturing lot, etc.) of the playback device 10 and is paired with the secret decryption key (kp (n)). It is what constitutes.
[0048]
Further, {X} Y described in this embodiment means that X is information that can be decrypted with a key Y so that it can be decrypted. Hereinafter, the same applies to this embodiment.
[0049]
Here, two certificates (data) used in a mutual authentication process (authentication process) to be described in detail later are prepared corresponding to one secret decryption key. As shown in the column. That is, the key memory 42 stores the certificate data (KPp (n, a)) as the class public key corresponding to the secret decryption key (kp (n)). In this embodiment, n is a natural number and a is 1 or 2.
[0050]
Such a secret decryption key (kp (n)) may be leaked or broken (decrypted) by an undesired operation or the like, and as shown in FIG. n), the playback device 10 is extended in life. A set of such a secret decryption key (kp (n)) and certificate data (KPp (n, a)) is given an identification number N (natural number) as shown in the right column of FIG. In the authentication process, the identification numbers N are used in ascending order.
[0051]
However, as described above, if a certificate that is no longer usable due to decryption or the like is used for authentication processing, the authentication fails, and the time required for the processing is wasted. That is, in the authentication process, the above-described certificate data (KPp (n, a)) is given to the memory card 12, and the certificate ID of the certificate data (KPp (n, a)) is included in the revocation list data. It detects (determines) whether the certificate is included and determines whether the certificate is correct (valid).
[0052]
Such an authentication process requires several seconds (2 to 3 seconds). For example, when the secret decryption key (Kp (1)) cannot be used at all and a part of the secret decryption key (Kp (2)) cannot be used, that is, when the certificate data (KPp ( (1,1)), (KPp (1,2)) and (KPp (2,1)) cannot be used, and authentication processing is performed in order from the certificate data (KPp (1,1)) corresponding to the identification number 1. Is executed, the authentication process fails three times, and about 10 seconds are wasted. That is, it takes a lot of time until the reproduction starts.
[0053]
To avoid this, this embodiment is the same in that the certificate data (KPp (n, a)) is used in ascending order of the identification number N, but the identification number N of the usable certificate is stored in the EEPROM 40. If the certificate data (KPp (n, a)) becomes unusable, that is, if the authentication process fails, the identification number N is updated and the (next) certificate corresponding to the updated identification number N is updated. The data (KPp (n, a)) is used for the authentication processing. In the subsequent authentication process, reference is made to the identification number N stored in the EEPROM 40 and the certificate data (KPp (n, a)) corresponding to the identification number N is used for the authentication process in order. Therefore, the certificate data (KPp (n, a)) which has become unusable is not used. This saves wasted time.
[0054]
Specifically, the reproduction process is executed according to the flowcharts shown in FIGS. Note that the reproduction process is executed by the CPU 18 and the DSP 30 provided in the reproduction device 10 and the controller 50 provided in the memory card 12, so that the process between the reproduction device 10 and the memory card 12 is separated by a dotted line so as to be understood. It is provided.
[0055]
Referring to FIG. 5, when the user selects a desired song (music) and inputs a reproduction instruction, CPU 18 starts processing and searches certificate usable in EEPROM 40 in step S1. That is, the identification number N stored in the EEPROM 40 is detected. In a succeeding step S3, the CPU 18 reads the certificate data (KPp (n, a)) corresponding to the detected identification number N from the key memory 42 and outputs it to the memory card 12.
[0056]
Therefore, the controller 50 receives the certificate data (KPp (n, a)) in step S5, and determines in step S9 whether the certificate data (KPp (n, a)) is valid. Specifically, the controller 50 refers to the revocation list data in the license memory 56, and determines whether or not the certificate ID of the certificate data (KPp (n, a)) is included in the revocation list.
[0057]
If “NO” in the step S7, that is, if the certificate ID of the certificate data (KPp (n, a)) is included in the revocation list data, although not shown, the controller 50 transmits Notifying the CPU 18 of the rejection, the CPU 18 determines that the certificate data (KPp (n, a)) is invalid, and updates the identification number N (increment N) in step S9. Subsequently, in step S11, the CPU 18 stores (overwrites) the updated identification number N in the EEPROM 40, and then returns to step S1. In other words, if the certificate is invalid (unusable), it is determined that the authentication process has failed, the identification number N is updated, and the certificate corresponding to the updated (next) identification number is used. The authentication process is executed again.
[0058]
On the other hand, if “YES” in the step S7, that is, if the certificate ID of the certificate data (KPp (n, a)) is not included in the revocation list data, the certificate data (KPp (n, a)) is determined to be valid, the controller 50 generates a common key (Ks1) unique to the session in step S13, and uses the generated common key (Ks1) as certificate data (KPp (n, a)). And encrypt it. Thereby, {Ks1} KPp (n, a) that can be decrypted with the secret decryption key (kp (n)) stored in the key memory 42 and paired with the certificate data (Kp (n, a)) is generated. Is done. Actually, {Ks1} Kp (n) is generated. Then, the controller 50 outputs {Ks1} Kp (n) to the playback device 10 in step S23.
[0059]
As described above, if the certificate is valid, it is determined that the authentication process has been successful, and the process moves to the next step. That is, in this case, since the identification number N is not updated, it can be said that the identification number N is specified by the identification number N updated immediately before. However, if the identification number N in the EEPROM 40 is not updated in this reproduction process, it can be said that the identification number N is specified again.
[0060]
Subsequently, the CPU 18 receives {Ks1} Kp (n) in step S17, and decrypts {Ks1} Kp (n) with the secret decryption key (Kp (n)) stored in the key memory 42 (plain culture). I do. As shown in FIG. 6, in a succeeding step S19, it is determined whether or not the music data instructed to be reproduced is encrypted music data. If “NO” in the step S19, that is, if it is not the encrypted music data, an output request of the music data instructed to be reproduced is transmitted to the memory card 12 in a step S21. Therefore, in step S23, the controller 50 acquires the music data from the memory 54 and outputs it to the playback device 10. Thereafter, as shown in FIG. 7, a reproduction process is performed in step S53.
[0061]
On the other hand, if “YES” in the step S19, that is, if it is the encrypted music data, a common key (Ks2) unique to the session is generated in a step S25, and the common key (Ks2) is encrypted with the common key (Ks1). Become That is, ｛Ks2｝ Ks1 is generated. Subsequently, in step S27, this {Ks2} Ks1 is output to the memory card 12.
[0062]
In step S29, the controller 50 receives {Ks2} Ks1, and decrypts (plaintext) with the common key (Ks1). Therefore, a common key (Ks2) is obtained. In a succeeding step S31, the controller 50 determines whether or not reproduction is impossible based on the restriction information (AC1). If "YES" in the step S31, that is, if the output of the content decryption key (Kc (n)) of the restriction information (AC1) is not permitted, or the output of the content decryption key (Kc (n)) is permitted. However, if the number control information is "00", it is determined that reproduction is not possible, and the process ends as shown in FIG.
[0063]
On the other hand, if “NO” in the step S31, that is, if the output of the content decryption key (Kc (n)) is permitted and the number-of-times restriction information is other than “00”, the number of reproductions is limited in a step S33. Determine if there is. If “NO” in the step S33, that is, if the number-of-times restriction information is “FF” and there is no restriction on the number of times of reproduction, the process directly proceeds to the step S37 shown in FIG. On the other hand, if “YES” in the step S33, that is, if the number-of-times limiting information is “01” to “FE”, it is determined that the number of times of reproduction is limited, and the number-of-times limiting information in the license memory 56 is determined in a step S35. After updating (counting down), the process proceeds to step S37.
[0064]
In step S37 shown in FIG. 7, the controller 50 acquires the content decryption key (Kc (n)) in the license memory 56 and the control information (AC2) of the playback device 10, and in step S39, acquires the session acquired earlier. The content decryption key (Kc (n)) and the control information (AC2) of the playback device 10 are encrypted with the unique common key (Ks2). Therefore, {Kc (n) // AC2} Ks2 is generated. Then, in step S41, the controller 50 outputs this {Kc (n) // AC2} Ks2 to the playback device 10.
[0065]
It should be noted that the notation of {X // Y} Z means that X and Y are pieces of information encrypted so that they can be decrypted with the key Z, respectively. Hereinafter, the same applies to this embodiment.
[0066]
Therefore, in step S43, the CPU 18 obtains {Kc (n) // AC2} Ks2, and decrypts (plaintext) {Kc (n) // AC2} Ks2 with the common key (Ks2). Subsequently, in step S45, the CPU 18 determines whether or not reproduction is impossible based on the control information (AC2). That is, with reference to time information given from a timer (not shown), it is determined whether or not the reproduction time limit of the reproduction device 10 has passed. If “YES” in the step S45, that is, if the reproduction time limit has passed, the process is terminated as it is. On the other hand, if “NO” in the step S45, that is, if the reproduction time limit has not passed, the CPU 18 requests the memory card 12 to output the encrypted music data ($ Data \ Kc (n)) in a step S47. In response, the controller 50 acquires the encrypted music data (¥ Data ¥ Kc (n)) in the memory 54 in step S49 and outputs it to the playback device 10.
[0067]
In response to this, the CPU 18 decrypts the encrypted music data (¥ Data ¥ Kc (n)) using the content decryption key (Kc (n)) previously obtained (at step S43) at step S51. Culture). Then, in step S53, the CPU 18 provides the DSP 30 with the music data and the decoding software for decoding the music data. Then, the music data is reproduced according to the above-described processing, and thereafter, the CPU 18 ends the reproduction processing.
[0068]
In this embodiment, the decoder software is provided to the DSP 30 after decrypting the encrypted music data. However, the decoder software may be provided before decrypting the encrypted music data.
[0069]
According to this embodiment, there is almost no need to perform authentication processing using a certificate that has already been revoked, so that useless authentication processing can be omitted and playback can be started in a short time.
[0070]
In this embodiment, the processing of encryption and decryption is performed by the CPU of the playback device and the controller of the memory card. However, such processing of encryption and decryption is relatively enormous and burdensome. Alternatively, a processor or logic for executing only such processing may be separately provided.
[0071]
Further, in this embodiment, the decoding software for decoding the music data is stored in the EEPROM of the reproducing apparatus. However, a dedicated ROM may be provided, or the decoding software may be stored in the memory of the memory card. You may do so.
[0072]
Further, in this embodiment, n secret decryption keys (2n certificates) are provided. The larger the value of n, the longer the life of the playback device can be, but the capacity of the key memory becomes too large. In addition, since the reproducing apparatus itself becomes expensive and becomes large, it is necessary to determine a value that satisfies both the prolongation of the life of the reproducing apparatus and the price reduction (or downsizing) of the reproducing apparatus.
[0073]
Furthermore, the content data is not limited to music data, and includes various data protected by copyright, such as image data, map data, and document data. When reproducing such image data, map data, and document data, the image, map, and document are respectively displayed on a display.
[Brief description of the drawings]
FIG. 1 is an illustrative view showing an electric configuration of a reproducing apparatus of the present invention;
FIG. 2 is an illustrative view showing a configuration of the reproducing apparatus shown in FIG. 1 embodiment as viewed from the front;
FIG. 3 is an illustrative view showing an electric configuration of a memory card detachably provided in the reproducing apparatus shown in FIG. 1 embodiment;
FIG. 4 is an illustrative view showing a list of secret decryption keys stored in a key memory of the playback apparatus shown in FIG. 1, a set of certificates corresponding to the keys, and identification numbers of the certificates;
FIG. 5 is a flowchart showing a part of reproduction processing of a CPU and a DSP of a reproduction apparatus and a controller of a memory card.
FIG. 6 is a flowchart showing another part of the reproduction processing of the CPU and DSP of the reproduction apparatus and the controller of the memory card.
FIG. 7 is a flowchart showing another part of the reproduction processing of the controller of the memory card and the CPU and DSP of the reproduction device.
FIG. 8 is an illustrative view showing one example of an electric configuration of a conventional data reproducing apparatus;
[Explanation of symbols]
10. Reproduction device
12 ... memory card
18 ... CPU
20 ... operation keys
24 ... analog input terminal
28… Display
30 ... DSP
40 ... EEPROM
42,58… Key memory
50… Controller
54… Memory
56 ... License memory

Claims (3)

A content reproducing apparatus that performs authentication processing using certificate data with a removable recording medium and reproduces the content of the recording medium when the authentication processing is successful.
Authentication means for executing the authentication processing in the order starting from the certificate data corresponding to the registered identification number,
If the authentication process fails, the identification means for identifying an identification number of unused certificate data, and an updating means for updating the registered identification number to the identification number identified by the identification means are provided. , Content playback device. The specifying means specifies an identification number of certificate data next to the certificate data for which the authentication processing has failed,
2. The content reproducing apparatus according to claim 1, wherein the updating unit updates the content each time the authentication process fails. The content reproducing apparatus according to claim 1, wherein the content is recorded on the recording medium in an encrypted state, and the content reproducing apparatus further includes a decryption unit configured to decrypt the content with a decryption key obtained by the authentication process.

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